Do bladesingers apply song of victory int mod to offhand bonus attack? Or still need two-weapon fighting style? The bonus attack doesn't add ability mod that you use for the attack, Can ability mod from other features be included in the attack?

— PoLo (@jaceimba) October 24, 2017

I believe so, unless they state otherwise

— Mike Mearls (@mikemearls) October 24, 2017